Issue #28492: Fix how StopIteration is raised in _asyncio.Future

1 files changed, 19 insertions, 2 deletions

diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index d1d9c54..d9fe63d 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -787,9 +787,26 @@ FutureIter_iternext(futureiterobject *it)
 
     res = FutureObj_result(fut, NULL);
     if (res != NULL) {
-        // normal result
-        PyErr_SetObject(PyExc_StopIteration, res);
+        /* The result of the Future is not an exception.
+
+           We cunstruct an exception instance manually with
+           PyObject_CallFunctionObjArgs and pass it to PyErr_SetObject
+           (similarly to what genobject.c does).
+
+           This is to handle a situation when "res" is a tuple, in which
+           case PyErr_SetObject would set the value of StopIteration to
+           the first element of the tuple.
+
+           (See PyErr_SetObject/_PyErr_CreateException code for details.)
+        */
+        PyObject *e = PyObject_CallFunctionObjArgs(
+            PyExc_StopIteration, res, NULL);
         Py_DECREF(res);
+        if (e == NULL) {
+            return NULL;
+        }
+        PyErr_SetObject(PyExc_StopIteration, e);
+        Py_DECREF(e);
     }
 
     it->future = NULL;